SACRAMENTO (CBS13) – Scientists say the Sacramento region could be facing its own “Big One” – and it’s not an earthquake.

The US Geological Survey says soil samples show that rainstorms have triggered “megafloods” here before. They say Sacramento was buried under 30 feet of water over 150 years ago.

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While that was long ago, scientists say it’s only a matter of time before another because atmospheric rivers are getting stronger.

Scientists say knowing evacuation routes is crucial.

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Meantime, the cleanup continues in Southern California after Friday’s 7.1 magnitude earthquake. Officials say nearly 6,000 aftershocks have rattled the area near Ridgecrest since Thursday.

Crews in Nevada are investigating a death that may be connected to the earthquake. The Nye County Sheriff’s Office says a 56-year-old man was working underneath a vehicle when it fell on him during the July 4 quake. His body was not found until Tuesday.

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The earthquake is the strongest to hit Southern California in 20 years.